I have the Shop Manual, and Parts list book. Neither seem to say. The rears are the same part number for both 1/2 and 3/4 tons. The front have different part numbers for 48-51 parts list book for the front wheels. But the 1/2 ton front cylinders part number is designated as a part that was not previously listed in a previous parts book.
The part # listed for for front left on 1/2 ton is 1271 433
The part # listed for for front right on 1/2 ton is 1271 432
The part # listed for for front left on 3/4 ton is 635 537
The part # listed for for front right on 3/4 ton is 635 536
page 55 of Dodge B-Series Trucks Restorer's and Collector's Reference Guide and History states:
Front Wheel Cylinders Double Acting Stepped Diameter Bore 1 1/4" x 1 3/8" for B,C, and D models.
I guess I had the answer all along, just needed to read the books I already had.
Thanks for the help.